maple_tree: preallocate nodes in mas_erase()

Use mas_wr_preallocate() in mas_erase() to preallocate enough nodes to
complete the erase.  Add error handling by skipping the store if the
preallocation lead to some error besides no memory.

Link: https://lkml.kernel.org/r/20240814161944.55347-7-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/maple_tree.c

@@ -6371,14 +6371,18 @@ void *mas_erase(struct ma_state *mas)
 
 	/* Must reset to ensure spanning writes of last slot are detected */
 	mas_reset(mas);
-	mas_wr_store_setup(&wr_mas);
-	mas_wr_store_entry(&wr_mas);
+	mas_wr_preallocate(&wr_mas, NULL);
 	if (mas_nomem(mas, GFP_KERNEL)) {
 		/* in case the range of entry changed when unlocked */
 		mas->index = mas->last = index;
 		goto write_retry;
 	}
 
+	if (mas_is_err(mas))
+		goto out;
+
+	mas_wr_store_entry(&wr_mas);
+out:
 	mas_destroy(mas);
 	return entry;
 }